The invention relates to a pump having an axial impeller with helical blades for sucking liquid through an intake opening that is arranged at a bottom side of the axial impeller.
A pump of this type has been described in DE 198 04 907 C1.
DE 1 806 195 B and U.S. Pat. No. 2,027,015 disclose pumps having a cutting axial impeller the blades of which are arranged to be in cutting relation, at the periphery of the axial impeller, with cutting edges formed at a wall of an intake-side pump housing or of an intake tube, respectively.
U.S. Pat. No. 6,406,635 B1 discloses a method for pumping cooling and lubricating liquids that are contaminated with metal chippings.
The invention is particularly concerned with a pump that is arranged at a base of a machine tool and serves for pumping cooling liquid for the machine tool, which is collected in a liquid reservoir in the machine base, so that the liquid may again be supplied to the machining tool, possibly with the aid of another pump. For that purpose, radial-type rotary pumps with open impeller blades have been proved to be particularly suitable, because they are relatively insensitive to articles such as chippings or the like that may be contained in the cooling liquid.
In the past years, machine tools have increasingly been used for machining light metal, such as aluminum, for example in automotive industry. The chippings that are created in machining of light metal may reach a considerable length.